In a classroom setting, students sit across the room and view teacher's presentation from different perspectives. For example, sometimes, the teacher's presentation can include writing and/or drawing on a whiteboard/blackboard, may be occluded or blocked by the teacher, other students, furniture and the like for students on one side of the room while students on the other side can see it clearly.
In addition, today's interactions between teachers and students can depend on the attention of the teacher. For example, when the teacher is busy explaining materials or demonstrating procedures, he/she may not be paying attention to the students. It is also common that the teacher may unintentionally ignore some students while interacting with others.